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GLOBECOM'05: IEEE Global Telecommunications Conference, 2005

作者： Gossain, Hrishikesh Cordeiro, Carlos Agrawal, Dharma P. OBR Center for Distributed and Mobile Computing Department of ECECS University of Cincinnati Cincinnati OH 45221-0030

ISBN: (纸本)0780394143

This paper addresses the issue of deafness and hidden terminal problem in a mobile Ad Hoc Networks (MANETs) using directional antennas. To minimize these effects, we propose a MAC protocol for directional Antennas (MDA) which employs an enhanced directional network allocation vector (NA V) scheme and, a novel technique of Diametrically Opposite Directions (DOD) transmission of RTS and CTS. We compare MDA with IEEE 802.11 and two recently proposed directional MAC protocols and results show that MDA outperforms these protocols in the majority of scenarios investigated. We also point out that the performance does depend on the network topology and the truffle pattern.

关键词： Network protocols

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Attribute allocation in large scale sensor networks 05

Attribute allocation in large scale sensor networks

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2nd International Workshop on Data Management for Sensor Networks, DMSN 2005, Held in Conjunction with Very Large Data Bases

作者： Biswas, Ratnabali Chowdhury, Kaushik Agrawal, Dharma P. OBR Research Center for Distributed and Mobile Computing Dept. of ECECS University of Cincinnati Cincinnati OH 45221-0030 United States

ISBN: (纸本)1595932062

Wireless sensor network is an emerging technology that enables remote monitoring of large geographical regions. In this paper, we address the problem of distributing attributes over such a large-scale sensor network so that the cost of data retrieval is minimized. The proposed scheme is a data-centric storage scheme where the attributes are distributed over the network depending on the correlations between them. The problem addressed here is similar to the Allocation Problem of distributed databases. In this paper, we have defined the Allocation Problem in the context of sensor networks and have proposed a scheme for finding a good distribution of attributes to the sensor network. We also propose an architecture for query processing given such a distribution of attributes. Finally, we present simulations results to illustrate the conditions under which our proposed architecture is beneficial. To the best of our knowledge, this is the first attempt to study the attribute allocation problem of distributed databases in the context of sensor networks. Copyright 2005 ACM.

关键词： Geographical regions

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Tree based data aggregation in sensor networks using polynomial regression

Tree based data aggregation in sensor networks using polynom...

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2005 8th International Conference on Information Fusion, FUSION

作者： Banerjee, Torsha Chowdhury, Kaushik Agrawal, Dharma P. University of Cincinnati OBR Center for Distributed and Mobile Computing Cincinnati OH 45221-0030 United States OBR Center for Distributed and Mobile Computing Department of Electrical and Computer Engineering and Computer Science University of Cincinnati Cincinnati OH 45221-0030 United States

ISBN: (纸本)0780392868

In this paper, we propose a tree based regression algorithm, (TREG) that addresses the problem of data compression in wireless sensor networks. By function approximation based on multivariable polynomial regression and passing only the coefficients returned by the regression function instead of aggregated data, TREG achieves the following goals: (1) the sink can get attribute values in regions devoid of sensor nodes for attribute values that show smooth spatial gradation (2) readings over any portion of the region can be obtained at one time by querying the root instead of flooding those regions, thus incurring significant energy savings. As size of the data packet transmitted from one tree node to another remains constant, the proposed scheme scales well with growing network density. Extensive simulations are performed on real world data to demonstrate the effectiveness of our aggregation algorithm. Results reveal that for a network density of 0.0025, the optimal tree-depth should be 4 in order to restrict the absolute error to less than a threshold of 6%. A data compression ratio of about 0.02 is achieved using our proposed algorithm, which is almost independent of tree depth. © 2005 IEEE.

关键词： Data reduction

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Effects of contention window and packet size on the energy efficiency of wireless local area network

Effects of contention window and packet size on the energy e...

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2005 IEEE Wireless Communications and Networking Conference, WCNC 2005: Broadband Wirelss for the Masses - Ready for Take-off

作者： Wang, Xiaodong Yin, Jun Agrawal, Dharma P. OBR Center for Distributed and Mobile Computing ECECS University of Cincinnati Cincinnati OH 45221-0030 United States

ISBN: (纸本)0780389662

This paper introduces an analytical model to investigate the energy efficiency of 802.11 distributed coordinated function (DCF). Many factors, such as the number of contending nodes, packet size, contention window, packet transmission collision probability and channel condition, that affect the energy efficiency of 802.11 DCF have been considered. We determine the packet transmission probability by a method simpler than the existing Markov chain model. This paper identifies the tradeoff in choosing packet size to optimize the energy efficiency of DCF in error-prone environments. The effects of contention window and packet size on the energy efficiency are obtained for both DCF basic mode and DCF with four-way handshaking. It is shown that under error-prone environments optimal packet size can improve more on the energy efficiency than optimal contention window. Combining both optimal contention window and optimal packet size can achieve the maximum optimization. To validate our analytical results, we have done extensive simulations, and they seem to match very well with the presented analytical results. © 2005 IEEE.

关键词： Wireless telecommunication systems

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Connectivity in multi-radio, multi-channel heterogeneous ad hoc networks

Connectivity in multi-radio, multi-channel heterogeneous ad ...

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2005 IEEE 16th International Symposium on Personal, Indoor and mobile Radio Communications, PIMRC 2005

作者： Cavalcanti, Dave Gossain, Hrishikesh Agrawal, Dharma OBR Center for Distributed and Mobile Computing Department of ECECS University of Cincinnati Cincinnati OH 45221-0030 United States Mesh Research and Development Group Motorola Inc. Maitland FL

ISBN: (纸本)3800729091

Future wireless networks are expected to integrate heterogeneous devices equipped with multiple radios and different characteristics. Therefore, it is important to understand how these heterogeneous radios can affect connectivity and overall multi-hop network performance. In this paper, we study the connectivity of a heterogeneous ad hoc network. We consider two types of nodes: nodes equipped with a single communication interface with communication range r, and Dual-Mode (DM) nodes, equipped with two communication interfaces with two different communication ranges r and rf, respectively, where r f>r. We assume the radios in the DM nodes operate in two different channels. We provide a theoretical analysis of connectivity in a linear network and we present simulation results for the two-dimensional case that show the impact of DM nodes on connectivity, broadcast latency and robustness in static scenarios. © 2005 IEEE.

关键词： Ad hoc networks

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A cross-layer approach for designing directional routing protocol in MANETs

A cross-layer approach for designing directional routing pro...

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2005 IEEE Wireless Communications and Networking Conference, WCNC 2005: Broadband Wirelss for the Masses - Ready for Take-off

作者： Gossain, Hrishikesh Joshi, Tarun Cordeiro, Carlos Agrawal, Dharma P. OBR Center for Distributed and Mobile Computing Department of ECECS University of Cincinnati Cincinnati OH 45221-0030 United States Philips Research Wireless Communications and Networking Department Briarcliff Manor NY 10510 United States

ISBN: (纸本)0780389662

In this paper we propose a Directional Routing Protocol (DRP) for MANETs. DRP is an on-demand directional routing protocol which assumes a cross layer interaction between routing and MAC layer. The main features of DRP include an efficient route discovery mechanism, establishment and maintenance of directional routing and directional neighbor tables (DRT and DNT respectively), and novel directional route recovery mechanisms. We have implemented DRP on top of an existing MAC protocol for directional antennas and have compared its performance with the popular dynamic source routing (DSR) protocol over both omni-directional and directional antenna models. Preliminary simulation results are found to be very promising. © 2005 IEEE.

关键词： Network protocols

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A credit-payment scheme for packet forwarding fairness in mobile ad hoc networks

A credit-payment scheme for packet forwarding fairness in mo...

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2005 IEEE International Conference on Communications, ICC 2005

作者： Yoo, Younghwan Ahn, Sanghyun Agrawal, Dharma P. OBR Center for Distributed and Mobile Computing Department of ECECS University of Cincinnati Cincinnati OH 45221-0030 School of Computer Science University of Seoul Seoul 130-743 Korea Republic of

Routing protocols for mobile ad hoc networks (MANETs) have assumed that all nodes voluntarily participate in forwarding others' packets. This was a reasonable assumption because all nodes in previous MANETs belonged to a single authority. In the near future, however, a MANET may consist of nodes that belong to multiple organizations since various civilian applications are expected to appear. In this situation, mobile nodes may deliberately avoid packet forwarding to save their own energy, resulting in network partition. To make nodes volunteer in packet forwarding we suggest a payment scheme called Protocol-Independent Fairness Algorithm (PIFA). In this type of schemes, nodes need credits to transmit their own packets, and this credit can be earned by forwarding others' packets. PIFA can be utilized irrespective of the type of basic routing protocols, while previous methods are compatible only with source routing like DSR. Simulation results show that PIFA can prevent network partition and network performance degradation due to selfish nodes by inducing them to participate in forwarding packets. © 2005 IEEE.

关键词： Packet networks

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An enhanced and energy efficient communication architecture for Bluetooth wireless PANs

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Ad Hoc Networks 2005年第2期3卷 119-140页

作者： Cordeiro, Carlos De M. Abhyankar, Sachin Agrawal, Dharma P. Networking Technologies Lab. Nokia Research Center Tampere Finland Qualcomm Incorporated San Diego CA United States OBR Ctr. Distributed Mobile Comp. Department of ECECS University of Cincinnati Cincinnati OH United States

Bluetooth is a radio technology for Wireless Personal Area Networking (WPAN) operating in the 2.4 GHz ISM frequency band, and allows devices to be connected into short-range ad hoc networks. The Bluetooth medium access control protocol is based on the Master/Slave paradigm wherein any communication between slave devices has to go through the Master. While this model provides for simplicity, it incurs a longer delay between any two slave devices due to far from optimal packet forwarding, the use of double the bandwidth, and also additional energy wastage at the Master. Moreover, if more than two devices want to communicate as a group, this can only be achieved by either multiple unicast transmissions or a piconet-wide broadcast, clearly resulting in inefficiency. In this paper, we propose a novel Dynamic Slot Assignment (DSA) scheme whereby the Master device dynamically assigns slots to Slaves so as to allow them to communicate directly with each other without any Master intervention. This proposed communication architecture also provides for Quality of Service (QoS) requests, admission control, and multi-device conversation by which a multicast-like communication is implemented within a piconet. Through extensive simulation, we observe that DSA drastically enhances Bluetooth performance in terms of delay and throughput, while significantly reducing power consumption at the master and the overall piconet. © 2004 Elsevier B.V. All rights reserved.

关键词： Radio systems

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Tree based data aggregation in sensor networks using polynomial regression

Tree based data aggregation in sensor networks using polynom...

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International Conference on Information Fusion

作者： T. Banerjee K. Chowdhury D.P. Agrawal OBR Center for Distributed and Mobile Computing University of Cincinnati Cincinnati OH USA

In this paper, we propose a tree based regression algorithm, (TREG) that addresses the problem of data compression in wireless sensor networks. By function approximation based on multivariable polynomial regression and passing only the coefficients returned by the regression function instead of aggregated data, TREG achieves the following goals: (1) the sink can get attribute values in regions devoid of sensor nodes for attribute values that show smooth spatial gradation (2) readings over any portion of the region can be obtained at one time by querying the root instead of flooding those regions, thus incurring significant energy savings. As size of the data packet transmitted, from one tree node to another remains constant, the proposed scheme scales well with growing network density. Extensive simulations are performed on real world data to demonstrate the effectiveness of our aggregation algorithm. Results reveal that for a network density of 0.0025, the optimal tree-depth should be 4 in order to restrict the absolute error to less than a threshold of 6%. A data compression ratio of about 0.02 is achieved using our proposed algorithm, which is almost independent of tree depth.

关键词： Intelligent networks Polynomials Regression tree analysis Function approximation Data compression Binary trees mobile computing distributed computing Wireless sensor networks Sensor phenomena and characterization

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Challenges in utilizing aggregate logical sensor units for wireless sensory information networks

Challenges in utilizing aggregate logical sensor units for w...

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2005 IEEE 16th International Symposium on Personal, Indoor and mobile Radio Communications, PIMRC 2005

作者： Kumar, Anup Dhekne, P.S. Agrawal, Dharma P. Lab. CECS University of Louisville Louisville KY 40292 Computer Division Mod Lab. BARC Mumbai India OBR Research Center for Distributed and Mobile Computing ECECS University of Cincinnati Cincinnati OH 45221-0030

ISBN: (纸本)3800729091

Historically, a large number of small and cheaper sensors are deployed to form a sensor network. This paper provides rationale behind using an Aggregate Logical Sensor Unit (ALSU) as a building block in a Wireless Sensory Information network (WSIN). In this architecture, a single ALSU is composed of many off-the-shelf sensor nodes in the manner similar to the Beowulf cluster concept. The highly capable, cost effective and flexible ALSUs built in this manner from several smaller physical sensor nodes, would enable high computation power and built-in reliability for sensor applications. The objective of this paper is to provide an alternative where energy and computation is not a limiting factor in order to achieve the operational objectives of WSIN applications. This paper highlights critical issues that need to be addressed in developing a framework where each ALSU could have the capability to perform required operations as dictated by an underlying application. © 2005 IEEE.

关键词： Wireless sensor networks

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